Many examples of ramp structures can be found in the prior art which differ considerably in design. For a manufacturer, it is desirable to design a ramp which is of low cost to manufacture, which makes use of readily available materials, and which has sufficient strength for many different applications when sold to customers. Due to the large size of many ramp structures, it is further desirable for ramps to be foldable into a collapsed storage position.
The following U.S. patents disclose various examples of folding ramp structures: U.S. Pat. No. 6,764,123 belonging to Bilyard; U.S. Pat. No. 5,988,725 belonging to Cole; U.S. Pat. No. 7,299,517 belonging to Adinolfe; U.S. Pat. No. 4,795,304 belonging to Dudley and U.S. Pat. No. 4,979,867 belonging to Best. In the prior art, known designs for ramp structures typically require custom manufacturing of many complex parts so that the resulting ramp structure is both costly to make and ship to customers.